Erosion rates are computed by a simplification of Partheniades (1962) results for

particle by particle erosion. The source term is computed by

⎛τ

⎞

⎜ - 1⎟,τ > τ e

⎜τ

⎟

⎝ e

⎠

where

=

erosion rate constant,

τe

=

critical shear stress for particle erosion.

In all cases, it is expected that Te > τ d . When bed shear stress is high enough to

cause mass failure of a bed layer, the erosion source term is

where

=

thickness of the failed layer,

ρL

=

density of the failed layer,

∆*t*

=

time interval over which failure occurs,

τs

=

bulk shear strength of the layer.

For modeling wind-wave resuspension where the primary goal is to reproduce water

column concentrations, an alternate clay transport formulation is provided where

erosion and deposition are taken as independent processes that can operate

simultaneously, and thus:

In this way the model can produce features such as steady-state water column

concentrations, deposition at relatively high shear-stresses, etc. The sediment system

is assumed to be composed of silt and clays represented by a single sediment class.

Deposition is similar to that of Option 1 except that depositional probabilities P

depend on τ such that:

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